<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<style type="text/css">
		div::before{
			content: '{';
			color: deeppink;
		}
		
		div::after{
			content: "}";
			color: skyblue;
		}
		/*::before, ::after 前面目标元素不写是默认为html*/
		
		input::-webkit-input-placeholder{
			/*存在兼容性问题 */
			color:white;
			background: #ccc;
		}
		
		input::selection{
			color: red;
			background: black;
		}
			
	</style>
	<body>
		<div>测试</div>
		<input type="text" name="" id="" value="" placeholder="aaa"/>
	</body>
</html>
